IEnumXXXX

To allow you to enumerate the number of items of a given type that an object maintains, COM provides a set of enumeration interfaces, one for each type of item.

To use these interfaces, the client asks an object that maintains a collection of items to create an enumerator object. The interface on the enumerator object is one of the enumeration interfaces, all of which have a name of the form IEnumItem_name. The only difference between enumeration interfaces is what they enumerate—there must be a separate enumeration interface for each type of item enumerated. All have the same set of methods and are used in the same way. For example, by repeatedly calling the Next method, the client gets successive pointers to each item in the collection.

The following table lists the set of enumeration interfaces that COM defines, and the items enumerated.

Enumeration Interface Name	Item Enumerated
IEnumFORMATETC	An array of FORMATETC structures.
IEnumMoniker	The components of a moniker, or the monikers in a table.
IEnumOLEVERB	The different verbs available for an object, in order of ascending verb number.
IEnumSTATDATA	An array of STATDATA structures that contain advisory connection information for a data object.
IEnumSTATSTG	An array of STATSTG structures that contain statistical information about a storage, stream, or LockBytes object.
IEnumString	Strings
IEnumUnknown	Enumerates IUnknown interface pointers.
IEnumVARIANT	A collection of Variants. It allows clients to enumerate heterogeneous collections of objects and intrinsic types when the clients cannot or do not know the specific type(s) of elements in the collection.

Methods in Vtable Order

IUnknown Methods	Description
QueryInterface	Returns pointers to supported interfaces.
AddRef	Increments reference count.
Release	Decrements reference count.

IEnumXXXX Methods	Description
Next	Retrieves a specified number of items in the enumeration sequence.
Skip	Skips over a specified number of items in the enumeration sequence.
Reset	Resets the enumeration sequence to the beginning.
Clone	Creates another enumerator that contains the same enumeration state as the current one.

Send comments about this topic to Microsoft.